Core: upgrade to Lucene 4.10.1 snapshot

Lucene will soon release official 4.10.1, but by upgrading sooner we can 1) sidestep the false failures due to the 1.8.0_20 JVM hotspot bug (has caused a number of false failures in recent Jenkins tests), 2) make sure none of the Lucene changes in 4.10.1 are problematic.

Closes #7844